For example, nothing says desperately clingy quite like Wisconsin's "Stay Just a Little Bit Longer."
"Kansas, as big as you think" reassures people who are insecure about their geographic knowledge. (It's about the same size as Nebraska, right?) But it does little to promote tourism. Anna Nicole Smith also might be as big as I think, but I wouldn't want to go on a vacation to see her.
South Carolina's "Smiling Faces. Beautiful Places." and South Dakota's "Great Faces. Great Places." are sure to lead to plagiarism accusations sooner or later. Also, someone should loan the folks in South Dakota a thesaurus, so they can come up with some new adjectives.
On the flip side, Idaho has a slogan that succinctly reflects what makes the state special: "Great Potatoes. Tasty Destinations."